This application is a 35 USC 371 of PCT/JP99/01677, filed Mar. 31, 1999.
The present invention relates to a strip wiper, strip wiping method, rolling facility, and rolling method.
In rolling operation, a rolling lubricant is supplied to the entrance of a rolling mill so as to reduce friction between the strip (rolled material) and the rolling work roll and to cool the work roll. Particularly, in cold rolling operation with a 20-high Sendzimir rolling mill having work rolls of extremely small diameter or a 6-high rolling mill having work rolls of small diameter, a lubricant is supplied also to the exit of the rolling mill so as to increase the cooling capacity of the work rolls.
Moreover, in the rolling of shadow mask materials by rolling mills, dull rolling with dull rolls is carried out in the final pass of rolling process so as to roughen the surface of the rolled material. In dull rolling like this, the surface of the rolled material is soiled with dull powder (powder fall off from the dull roll) and hence a rolling lubricant is supplied to the exit of the rolling mill to wash out the dull powder.
The rolling mills supplied with a lubricant as mentioned above yield rolled strips carrying a large amount of lubricant on their surface. When a strip is wound into a coil, with its surface carrying a large amount of rolling lubricant supplied at the entrance of the roll mill, particularly at the exit of the roll mill, the wound coil becomes a xe2x80x9ctelescopexe2x80x9d, with each layer slipping sideward due to rolling lubricant present between layers. The telescoped coil leads to meandering and irregular forms, inhibiting stable rolling operation.
Also, in the case where there exists bridle rolls (to add tension to the strip) at the exit of the rolling mill, the rolling lubricant extremely decreases the coefficient of friction between the bridle rolls and the strip, disabling stable operation (as in the case mentioned above) due to insufficient tension.
It is the strip wiper that removes the rolling lubricant from the strip surface. The strip wiper is available in different types, such as tube wiper, roll wiper, and air-jet wiper.
A tube wiper is highly capable of wiping but its tube is short in life when foreign matter (such as dust) enters it. This is significant particularly in the case of high-speed operation. A tube wiper for dull rolling has the disadvantage of impairing the surface quality of the rolled material due to tube clogging with dull powder.
As a substitute for this, a roll wiper has been proposed in Japanese Patent Publication No. 60403/1990. It is designed to improve the wiping capacity by pressing the staggered split back-up rolls individually with springs, thereby distributing the pressing force toward the trip uniformly in the widthwise direction. The disadvantage of this system is that the wiper roll is bent by the supporting force of the back-up roll extending outside the strip width, resulting in a poor shape with an elongated end, if the pressing force is strong. This wiper roll, therefore, is poor in wiping ability due to limited pressing force. At the time of high-speed operation, the wiper roll, which is not driven, does not rotate due to hydroplaning which results from the fact that the rolling lubricant on the roll surface forms an oil film between the roll and the strip. The result is incomplete wiping, or the non-rotating roll scratches the strip surface. In addition, this roll wiper is liable to stop because of many back-up rolls and its comparatively high bearing seal resistance.
In order to address this problem, there has been proposed a roll wiper (having a wiper roll supported by an air bearing) in Japanese Patent No. 2523725. It has a small diameter for good wiping performance because it is supported uniformly on its surface by an air bearing. In addition, the roll wiper of air bearing type has its roll floated and supported by high-pressure air, so that it has a very low rolling friction. It remains turning at speeds as high as 700 m/min, and hence it is suitable for high-speed rolling.
Unfortunately, the roll wiper of air beating type has never been put to practical use because of its low wiping performance which results from the fact that the air bearing is lower in its load capacity than the static bearing of hydraulic type. (It is to be noted that the air pressure for the air bearing is usually lower than 5 kgf/cm2, whereas the hydraulic pressure is as high as 100 kgf/cm2.) Another problem is that the air bearing of one-pocket type is low in rigidity in the horizontal direction and hence the roll comes into contact with the bearing when it receives even a slight horizontal force. This prevents normal operation. The roll rotating at high speeds affects the air flow in the beating (making the air flow asymmetric in the bearing), reducing further the horizontal rigidity to allow the roll to come into contact with the bearing.
For the reasons mentioned above, it is desirable to propose a high-speed roll wiper capable of better wiping than the conventional tube wiper, by increasing the load capacity of the air bearing and preventing the excessive pressure at edges.
It is an object of the present invention to provide a strip wiper device highly capable of removing liquid from the strip surface, a method for strip wiping, a rolling facility, and a rolling method.
The present invention is directed to a strip wiper device to remove liquid from the strip surface which comprises a wiper roll to remove liquid from the strip surface and a fluid bearing to support the wiper roll, with the fluid bearing having at least two fluid passages in the circumferential direction of the roll.
The present invention is directed to a strip wiper device to remove liquid from the strip surface which comprises a first strip wiper and a second strip wiper which are arranged sequentially in the direction of strip advance, the second strip wiper being made up of a wiper roll and a fluid bearing to support the wiper roll, with the fluid bearing having at least two fluid passages in the circumferential direction of the roll.
The present invention is directed also to a strip wiper device to remove liquid from the strip surface which comprises a first strip wiper and a second strip wiper which are arranged sequentially in the direction of strip advance, the second strip wiper being made up of a wiper roll and a fluid bearing to support the wiper roll, with the fluid bearing having at least two fluid passages in the circumferential direction of the roll.
The present invention is directed also to a strip wiper device to remove liquid from the strip surface in cold rolling which comprises a first strip wiper for rough wiping and a second strip wiper for finishing which are arranged sequentially in the direction of strip advance, the second strip wiper being made up of a wiper roll and a fluid bearing to support the wiper roll by pneumatic pressure, with the fluid bearing having at least two fluid passages (for pneumatic pressure to the wiper roll) in the circumferential direction of the roll, such that the wiper roll is supported by pneumatic pressure in two directions from the two fluid passages.
The present invention is directed also to a strip wiper device to remove liquid from the strip surface which comprises a first strip wiper and a second strip wiper which are arranged sequentially in the direction of strip advance, the first and second strip wipers each being made up of a wiper roll and a fluid bearing to support the wiper roll, with the fluid bearing having at least two fluid passages in the circumferential direction of the roll.
The present invention is directed also to a strip wiper device to remove liquid from the strip surface which comprises a first strip wiper and a second strip wiper which are arranged sequentially in the direction of strip advance, the second strip wiper being made up of a wiper roll and a fluid bearing to support the wiper roll.
The present invention is directed also to a method of strip wiping to remove liquid from the strip surface which is characterized in that wiper rolls supported by fluid bearings are arranged up and down, with the fluid bearing having at least two fluid passages in the circumferential direction of the roll, the fluid passage is supplied with a fluid so that the wiper roll is born by the fluid and is pressed against the strip.
The present invention is directed also to a method of strip wiping to remove liquid from the strip surface which is characterized in that a wiper roll for rough wiping removes liquid from the strip surface and wiper rolls supported by fluid bearings are arranged up and down at the downstream side, with the fluid bearing having at least two fluid passages in the circumferential direction of the roll, the fluid passage is supplied with a fluid so that the wiper roll is born by the fluid and is pressed against the strip.
The present invention is directed also to a rolling facility which comprises a rolling mill and a strip wiper device to remove liquid from the strip surface at the exit of the rolling mill, said strip wiper device being made up of a wiper roll to remove liquid form the strip surface and a fluid bearing to support the wiper roll, with the fluid bearing having at least two fluid passages in the circumferential direction of the roll.
The present invention is directed also to a rolling method to be applied to a rolling facility made up of a rolling mill and a strip wiper device to remove liquid from the strip surface at the exit of the rolling mill, said method being characterized in that wiper rolls supported by fluid bearings are arranged over and under the strip, the fluid bearing has at least two fluid passages in the circumferential direction of the roll and the passages are supplied with a fluid so that the wiper roll is born by the fluid, and the wiper roll is pressed against the strip so that liquid is removed from the strip surface while rolling is carried out.
The present invention is directed also to a rolling method to be applied to a rolling facility made up of a rolling mill and a strip wiper device to remove liquid from the strip surface at the exit of the rolling mill, said method being characterized in that a wiper roll for rough wiping removes most liquid from the strip surface, wiper rolls supported by fluid bearings are arranged over and under the strip, the fluid bearing has at least two fluid passages in the circumferential direction of the roll and the passages are supplied with a fluid so that the wiper roll is supported in two directions by pneumatic pressure, and the wiper roll is pressed against the strip so that liquid remaining unremoved by the wiper for rough wiping is removed from the strip surface while rolling is carried out.
The present invention is directed also to a strip wiper device which comprises a wiper roll to remove liquid from the strip surface and a fluid bearing to support the wiper roll, said fluid bearing having at least two fluid jet nozzles toward the wiper roll in the circumferential direction of the roll.
The present invention is directed also to a strip wiper device which comprises a wiper roll to remove liquid from the strip surface and a fluid bearing to support the wiper roll, said fluid bearing having at least one each fluid jet nozzle at the entrance and exit from the wiper roll axis center.
The present invention is directed also to a strip wiper device which comprises a wiper roll to remove liquid from the strip surface and a fluid bearing to support the wiper roll, said fluid bearing having at least two fluid jet nozzles toward the wiper roll in the circumferential direction of the roll, said jet nozzles being arranged such that their jet direction is toward the wiper axis center.